#ifndef GENALLOC_H
#define GENALLOC_H

/*
 *  Revision 20210307, Erwin Hoffmann
 *  - 
*/

#include <sys/types.h>

/* GEN_ALLOC demystified: 
   
   GEN_ALLOC generates a list of self-defined types (structs) in an
   allocated contiguous heap chunk while copying the content of the 
   entire field members or appending the existing field.
   GEN_ALLOC types care of currently used and/or allocated bytes of field.

Macros: 
  GEN_ALLOC_ready    (ta,type,field,len,a,i,n,x,base,ta_ready)
  GEN_ALLOC_readyplus(ta,type,field,len,a,i,n,x,base,ta_rplus)
  GEN_ALLOC_append   (ta,type,field,len,a,i,n,x,base,ta_rplus,ta_append) 

   0. ta: 'type alloc' - typedef'ed struct name (aka ipalloc et al.)
   1. type: defined struct (used for size information) 
   2. field: declared public name of struct
   2. len: used length of string 
   4. a: allocated size
   5. i: current allocated size for member x
   6. n: bytes to allocate; in 'ready' mode: +size of one entry;
                            in 'readyplus' mode: +size of +used size of one entry
   7. x: local name (alias to field name)
   8. base: size of single entry
   9. ta_ready/ta_readyplus (operation)
  10. ta_append (operation)

*/

/* file: gen_alloc.h */
#define GEN_ALLOC_typedef(ta, type, field, len, a) \
  typedef struct ta {                              \
    type *field;                                   \
    unsigned int len;                              \
    unsigned int a;                                \
  } ta;

/* file: gen_allocdefs.h   (deprecated) */
// used in: ipalloc, prioq, qmail-remote, qmail-inject, token822
#define GEN_ALLOC_ready(ta, type, field, len, a, i, n, x, base, ta_ready)         \
  int ta_ready(x, n)                                                              \
  register ta *x;                                                                 \
  register unsigned int n;                                                        \
  {                                                                               \
    register unsigned int i;                                                      \
    if (x->field) {                                                               \
      i = x->a;                                                                   \
      if (n > i) {                                                                \
        x->a = base + n + (n >> 3);                                               \
        if (alloc_re(&x->field, i * sizeof(type), x->a * sizeof(type))) return 1; \
        x->a = i;                                                                 \
        return 0;                                                                 \
      }                                                                           \
      return 1;                                                                   \
    }                                                                             \
    x->len = 0;                                                                   \
    return !!(x->field = (type *)alloc((x->a = n) * sizeof(type)));               \
  }

#define GEN_ALLOC_readyplus(ta, type, field, len, a, i, n, x, base, ta_rplus)     \
  int ta_rplus(x, n)                                                              \
  register ta *x;                                                                 \
  register unsigned int n;                                                        \
  {                                                                               \
    register unsigned int i;                                                      \
    if (x->field) {                                                               \
      i = x->a;                                                                   \
      n += x->len;                                                                \
      if (n > i) {                                                                \
        x->a = base + n + (n >> 3);                                               \
        if (alloc_re(&x->field, i * sizeof(type), x->a * sizeof(type))) return 1; \
        x->a = i;                                                                 \
        return 0;                                                                 \
      }                                                                           \
      return 1;                                                                   \
    }                                                                             \
    x->len = 0;                                                                   \
    return !!(x->field = (type *)alloc((x->a = n) * sizeof(type)));               \
  }

#define GEN_ALLOC_append(ta, type, field, len, a, i, n, x, base, ta_rplus, ta_append) \
  int ta_append(x, i)                                                                 \
  register ta *x;                                                                     \
  register type *i;                                                                   \
  {                                                                                   \
    if (!ta_rplus(x, 1)) return 0;                                                    \
    x->field[x->len++] = *i;                                                          \
    return 1;                                                                         \
  }

#endif